The present invention relates to a motor vehicle, and in particular to an active front steering system for a motor vehicle.
Active front steering systems for motor vehicles are used to rotate the wheels of the vehicle at a rate that is independent from the rotation of the steering wheel of the vehicle or without rotation of the steering wheel. The ratio of the rotation of the steering wheel to the rotation of the wheel defines a steering ratio. The active front steering system therefore sets the steering ratio of the vehicle. Without the active front steering system, the steering ratio is typically only determined by the ratio set by the mechanical connections between the steering wheel and the wheel of the vehicle.
Heretofore, active front steering systems have included a powered actuator operably connected to a pinion of a rack-and-pinion system of a vehicle. The active front steering system assists in pivoting the steerable wheels. In basic operation, the active front steering system typically alters (either positively or negatively) a driver input control angle from the driver as applied to the steering wheel, via the powered actuator, to rotate the wheels according to the steering ratio.
During off road operation, obstacles may be encountered by a vehicle. If the obstacle is sufficiently large and/or the friction generated by the tire is sufficiently low, the wheel will be unable to climb over the object. Such obstacles impede vehicle progress and may cause difficulty in controlling the vehicle.